Fun With var // nipafx

Fun With var

source code

Want to play around with the code yourself? Check out the repository Java X Demo, a project showcasing all important Java 9-16 features - it contains many of the snippets shown in this talk. It has a permissive license, so you can reuse the code for your projects.

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Since Java 10 you can use var to let the compiler infer a local variable's type:

var users = new ArrayList<User>();

And that's pretty much it, right? Surprisingly, no! There are a lot of details to consider...

is this JavaScript?!
how exactly is the type inferred?
where can I use var and what should I look out for?
won't this lead to unreadable code?

... and a few fun things to do with var...

playing with anonymous classes (don't!)
faking traits (don't!)
faking intersection types (do!)

After this live-coding deep dive into var, you'll know all about Java 10's flagship feature.

▚Slides

Here's the current version of the slides.

I also embedded them below. If they're focussed, you can navigate with arrow keys or swipes (they're two-dimensional, with chapters on the horizontal axis and chapter content layed out vertically). Use Page Up/Down for linearized order and ? for more shortcuts.